Vitamix. Totally amazing and will cook it at the same time as blending it so I just put in cold water, stock cube, raw veg (potatoes need cooking first but other veg doesn't) etc and stick it on. Hot, perfectly blended soup in a few minutes. It's expensive but we use it everyday for soups, smoothies, sauces, chopping veg and frothy hot milky drinks. Absolutely love it.
Very easy to clean too - half fill it with hot water and a squirt of washing up liquid and turn it on for a few seconds then rinse. No awkward parts. Sorry I sound like I'm selling them - I'm not, but just bought it recently and love it!
Mine's a Braun but it is so old now I think it's just gone blunt. Only one speed too. I don't want an entire soup machine as I have so many gadgets already. I'll have a look at the newer Brauns, might wait for Black Friday.
I've been using a Tesco value stick blender recently and it works brilliantly, really smooth soup. You can't adjust the speed and its a bit trickier to clean as it doesn't come apart like more expensive blenders but I think it cost less than a tenner so can't really complain.
I have a stick blender. It's a Braun one I got as a wedding present 14 years ago and I use it all the time. It's a fairly good one with a metal rather than plastic stick though so I don't know if that makes a difference.